The medical term for a toe or finger is a phalange and any individual bone within a toe or finger is called a phalanx. Deformities of the phalanges are common conditions encountered by surgeons. These deformities can occur for numerous reasons and the deformities have acquired different names such as mallet toe, claw toe, hammertoe, boutonniere deformity, and swan neck deformity, amongst others. Surgeons often address these deformities surgically in an attempt to straighten the phalanges, to alleviate pain, provide stability to the digit, improve ambulation, gait, or dexterity, or prevent further sequelae of phalangeal deformities.
The fixation of bone fractures or surgically manipulated bones with orthopedic hardware such as screws, plates, pins, and staples helps bone to heal. Bone fixation was originally accomplished with externally applied casts or other forms of immobilization which led to high rates of nonunion or malunion as these forms of immobilization afforded little inherent stability at the bone-bone interface. Stability is a critical factor for obtaining consolidation or bone healing. Eventually metallic rods and pins were utilized to increase stability of bone fixation thereby improving healing rates. Eventually further stability was gained through the use of screws across bone and joint surfaces because they added a compressive force across the opposing bone surfaces. Further improvements were made to screws via cannulation which allowed the more rapid placement of the screws, more accuracy, and greater ease of use whether for the repair of fractures or fusing the bones of a joint.
Of particular interest is the fusion of the proximal interphalangeal joint (PIPJ) of the toes and fingers for stabilizing and correcting deformity of these structures. The procedure normally involves resecting or cutting away the joint surfaces of the PIPJ. The two phalanx bones are then placed end to end and a rod or pin is then driven axially along the internal diameter of the phalange providing stability for osteosynthesis. One end of the pin typically remains outside of the skin of the phalange at the tip of the toe or finger during the healing process.
There is concern for many surgeons about the use of pins with this type of surgery because an exposed pin at the distal toe tip may increase the risk of pin tract infections. There is also the possibility of undesired migration of the pins deeper into a bone or the accidental removal of the pin prior to healing of the bone ends. Placing the pin through the skin like this also introduces the pin across the distal interphalangeal joint (DIPJ) and thus violates that joint. Also, the use of pins provides no rotational stability and may allow the phalangeal bones to “piston” on the pin because it is smooth. Therefore some surgeons look toward devices that can be introduced across the PIPJ alone so they do not stick out through the skin, do not violate the DIPJ or the metatarsal phalangeal joint (MTPJ), do not increase the risk for infection, and will provide stability in all planes. However, though there is some legitimacy to these concerns, the use of pins is often necessary when performing toe or finger surgery.
There are times when the surgery for reduction of a toe or finger deformity requires more than just a joint fusion of the PIPJ for proper correction. The release of ligaments and the transfer of tendons are sometimes necessary more proximally at the MTPJ adjacent to the PIPJ or at the DIPJ. This is done at the surgeon's discretion as he or she sees fit and may thus require the use of a pin across one or both of these joints to provide fixation and stability. The DIPJ and MTPJ are rarely fused. Surgeons currently have the option to use a pin and accept its disadvantages, or use some other commercially available product without the use of a pin, each of these having their own disadvantages.